The Minimal Dimension of Entangled-Noise Advantage

Abstract:Can entangled noise erase entanglement more efficiently than separable noise? Standard robustness restricts the added noise to separable states; generalized robustness allows any state. We prove that the two costs coincide for every two-qubit state and give an explicit full-rank qubit--qutrit state with a strict gap. Positivity under partial transpose (PPT) characterizes separability in both dimensions, so the boundary is not caused by a failure of the PPT criterion. Instead, product-vector geometry permits a rank-one bridge between the two-qubit dual optimizations and supplies a two-dimensional completely entangled subspace for the qubit--qutrit separation. Local isometric embeddings complete the finite-dimensional bipartite classification, also for any fixed multipartite cut. Combined with known three-qubit separation, the result classifies universal equality relative to full separability in all finite multipartite systems.

arXiv:2609.28367 [quant-ph]

(or arXiv:2609.28367v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2609.28367 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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